In a single chain silicate, how many of the oxygen atoms in each silica tetrahedron are shared with neighboring silica tetrahedra?
a. None
b. One
c. Two
d. Three
e. Four
The correct answer and explanation is :
The correct answer is b. One.
Explanation:
A silica tetrahedron is a basic structural unit of silicate minerals, consisting of a central silicon (Si) atom surrounded by four oxygen (O) atoms, forming a tetrahedral shape. Silicate minerals are classified based on how these silica tetrahedra are connected to each other. The primary classification includes isolated tetrahedra, single chains, double chains, two-dimensional sheets, and three-dimensional frameworks.
In a single chain silicate, also known as inosilicates, the tetrahedra are linked together by sharing one oxygen atom between neighboring tetrahedra. This arrangement forms a chain-like structure, where each tetrahedron shares one oxygen atom with the next, leading to a chain of linked tetrahedra.
Here’s how it works:
- Each silica tetrahedron has four oxygen atoms (SiO₄) and shares one oxygen with the adjacent tetrahedron. This shared oxygen connects the two tetrahedra, forming a chain.
- The unshared oxygen atoms are typically bonded to cations (such as metals or alkali elements) or are part of the crystal structure, providing stability.
This single chain structure leads to a one-dimensional arrangement of silica tetrahedra, with each tetrahedron connecting to two neighbors—one on either side—by the shared oxygen atoms.
In other silicate structures:
- Isolated tetrahedra (nesosilicates) do not share any oxygen atoms.
- Double chains (inosilicates) involve two chains of tetrahedra, where each tetrahedron shares two oxygen atoms with neighboring tetrahedra.
- Two-dimensional sheets (phyllosilicates) involve sharing three oxygen atoms.
- Three-dimensional frameworks (tectosilicates) involve all four oxygen atoms being shared, as seen in minerals like quartz.
Thus, in a single chain silicate, the correct answer is that one oxygen atom from each tetrahedron is shared with a neighboring tetrahedron.